Preheat oven to 350°F. Line an 8-inch square baking pan with parchment paper, leaving an overhang on two sides.
In a medium bowl, whisk together the flour, oats, baking soda, and salt.
In a large bowl, whisk together melted butter and both sugars until combined. Add the egg and vanilla extract and whisk until smooth.
Add the dry ingredients to the wet ingredients and stir until just combined. Don't overmix!
Fold in the chocolate chips.
Spread the batter evenly into the prepared pan and bake for 25-30 minutes, or until golden brown and a toothpick inserted into the center comes out clean. Allow to cool completely before cutting into bars.
Interesting Facts
These oat and chocolate chip bar cookies are vegan-friendly if you use vegan chocolate chips and butter.
You can easily customize these bars with other mix-ins like nuts, dried fruit, or even peanut butter chips.
This recipe makes about 16 bars, but you can easily double the recipe to make a larger batch.